Phase control device

ABSTRACT

A phase control device, for providing a plurality of phase values, for utilization by any system having a number of input/output ports with signals requiring control of their relative phases. The phase control device is constructed from phase shift elements electrically connected to a system of electrically interconnected switches separated off from the phase shift elements. The result is a reduction in the number of phase shift elements and switches as compared to conventional phase shifters and a simplification of the resulting architecture, a feature of significant importance in chip miniaturization.

FIELD OF THE INVENTION

The present invention relates to phase control devices in general andphase control devices as applied to phased array antennas in particular.

BACKGROUND OF THE INVENTION

Phase control devices play an important role in radar and communicationsin general, and in satellite communications in particular. There areknown in the art, planar phased array antennas for communicating withsatellites which are mountable on moving platforms. For certain of suchapplications the planar phased array antenna may comprise severalhundred radiating elements. This results in the use of a correspondingseveral hundred phase shifters, one for each radiating element. Owing tothe large number of phase shifters required, the phased arraysthemselves are therefore expensive.

There is, therefore, a need for reducing the number of phase shiftersrequired for a given number of radiating elements of a phased array.

SUMMARY OF THE INVENTION

In the following description and claims reference is made to phaseshifters and to phase control devices as applied to phased arrayantennas. This is done for clarity of illustration only and should in noway be interpreted as a limiting property of the phase control devicesof the invention which can be utilized by any system having a pluralityof input/output ports with signals requiring control of their relativephases.

In referring to phase shifters reference is implicitly made to the phaseshift elements and switches constituting the phase shifters; hencereducing the number of phase shifters required for a given task impliesreducing the number of constituent phase shift elements and switches.

It is an object of the present invention to provide a phase controldevice which reduces the number of phase shifters required in a givenapplication as compared to prior art techniques. In addition to thereduction in the number of phase shift elements and switches, anotherobject of the present invention is the simplification of the resultingarchitecture wherein the reduced number of phase shift elements isseparated off from the reduced number of switches, a feature ofsignificant importance in chip miniaturization.

In accordance with the present invention there is provided a phasecontrol device for providing a plurality of phase values, comprising:

a plurality of electrically interconnected phase shift elements; and

a plurality of switches electrically interconnected by a plurality offirst conducting lines and a plurality of second conducting lines, saidplurality of switches electrically connected to said plurality of phaseshift elements by means of said plurality of second conducting lines.

If desired the phase shift elements and the switches may be partitionedinto phase control units, the phase shift elements in each phase controlunit being electrically interconnected and the switches in each phasecontrol unit being electrically interconnected, only to switches withinthe same phase control unit and to the phase shift elements thereof.

Further, if desired, all the phase control units are parallellyconnected.

Optionally, all the phase control units are serially connected.

Alternatively, some of the phase control units are serially connectedwhereas others are parallelly connected.

Also, if desired, the phase control units may be connected to theswitches of a further phase control unit.

In a specific application of the invention the phase shift elements, theswitches and the first conducting lines are disposed on one side of adielectric plate; whereas the second conducting lines are disposed onthe opposite of said dielectric plate.

In accordance with one embodiment of the present invention the phasecontrol device further comprises, in a piecewise layered formation, aplurality of dielectric plates, each having front and rear faces, andwherein said plurality of phase shift elements, said plurality of firstconducting lines and said plurality of second conducting lines aredisposed on the faces of said dielectric plates.

In accordance with one embodiment of the invention the phase shiftelements are serially connected.

In accordance with another embodiment of the invention the phase shiftelements are parallelly connected.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding, the invention will now be described, by wayof a non-limiting example only, with reference to the accompanyingdrawings in which:

FIG. 1 shows an illustrative block diagram of a phased array antennawith each radiating element connected to a phase shifter;

FIG. 2 shows a typical M-stage phase shifter;

FIG. 3a shows a single phase shifter of an M-stage phase shifter in the“off” state;

FIG. 3b shows a single phase shifter of an M-stage phase shifter in the“on” state;

FIGS. 4a and 4 b illustrate the terminology for counting the number ofswitches;

FIG. 5 shows an illustrative block diagram of a phased array antennawith a switching circuit and a phase shift unit;

FIG. 6 illustrate the structure of a phase control device;

FIG. 7 shows a perspective view of a portion of a phase control devicein accordance with one embodiment of the present invention;

FIG. 8 shows a schematic block diagram of a phase control device;

FIG. 9 shows a schematic block diagram illustrating phase compensationfor a phase control device in accordance with one embodiment of thepresent invention;

FIG. 10 shows an illustrative block diagram of a phase control devicewith a parallelly connected phase shift unit; and

FIG. 11 shows a cascade configuration of serially connected phasecontrol devices.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Attention is first drawn to FIG. 1, showing an illustrative blockdiagram of a phased array antenna 1, comprising N radiating elements 2,designated by RI (I-1, . . . , N), each connected via a correspondingphase shifter 4 to a power divider/combiner 6. Since there is a phaseshifter connected to each radiating element there are N phase shifters,designated by PI (I=1, . . . , N).

FIG. 2 shows a typical multi-stage M-stage phase shifter 10, comprisingM phase shift elements 12, designated by PEJ (J=1, . . . , M), referenceelements 22. switches 14 for introducing either the phase shift elementsor the reference elements into the electrical path between theinput/output ports 20, control units 16, for operating the switches anda control bus 18 connected to the control units. Each phase shiftelement 12 introduces a different phase shift in the current flowingthrough it in relation to a current flowing through a corresponding oneof the reference elements 22.

FIG. 3a shows a single phase shifter 30 of a multi-stage phase shifter,of the type shown in FIG. 2, in the “off” state, wherein a certain phaseis introduced in a current flowing through the reference element 22. Thecurrent enters and exits the switch through the switch's input/outputports 31. On the other hand, FIG. 3b shows the single phase shifter 30in the “on” state, wherein a different phase is introduced in thecurrent flowing through the phase shift element 12. The single phaseshifter 30 comprises two input and two output switches 14, either ofwhich can serve as the input switch or the output switch since the phaseshifter is bi-directional.

The terminology for counting the number of switches is illustrated inFIGS. 4a and 4 b. In FIG. 4a, there are two switches, since circuit 40can be brought into electrical connection with two circuits 41 and 42,whereas in FIG. 4b, there is only a single switch since circuit 40 canbe brought into electrical contact with only a single circuit 43. In aunidirectional phase shifter the number of switches can be reduced byreplacing its two output switches with a balanced combiner but thisresults in losses within the combiner. However, a unidirectional phaseshifter, when used in bi-directional applications, adds at least twoswitches external to the phase shifter (see, for example, British PatentNo. 2158997 A). On the other hand, in some implementations, such as in alow-pass high-pass phase shifters, there are as many as six switches.Hence, in general, phase shifters of interest can have all in all two tosix switches. In the following description, phase shifters having fourswitches will be considered.

Returning to the M-stage phase shifter shown in FIG. 2, it is clear thatit contains a total of 4M switches. The number of phase combinations Pobtainable from an M-stage phase shifter is given by P=2^(M). Thisrelation can be derived by counting the number of combinations of “on”and “off” states of the M single phase shifters comprising the M-stagephase shifter. Hence, in a phased array antenna, whether it be linear orplanar, comprising N separately controlled radiating elements, eachconnected to an M-stage phase shifter, there are a total of 4MN switchesand MN phase shift elements. Furthermore, each M-stage phase shifterprovides 2^(M) phase values, giving a total of 2^(M)N phase values forthe whole antenna. In phased array antennas in general, and microwaveand millimeter wave phased array antennas in particular, there are alarge number of radiating elements and a correspondingly large number ofphase shifters. A large number of phase shifters (in the above example NM-stage shifters) not only results in the antenna being expensive, butalso introduces a redundancy in the design of the phased array owing tothe presence of a large number of identical phase shift elements.

The present invention reduces the number of switches and phase shiftelements required for a given phased array antenna by providing one setof phase shift elements that are shared by all the radiating elements.This is attained by connecting the set of phase shift elements to asystem of switches which in turn is connected to the radiating elementsof the phased array antenna.

Attention is now drawn to FIG. 5 showing an illustrative block diagramof a phased array antenna 50, comprising N radiating elements 51,designated by RI (I=1, . . . , N), connected each to a switching circuit52 which is in turn connected to a phase shift unit 53. The switchingcircuit 52 and the phase shift unit 53 taken together, constitute thephase control device of the invention. FIG. 6 illustrates the structureof the phase control device 60 in accordance with one embodiment of theinvention. The phase shift unit 53, in accordance with this embodiment,comprises a plurality of phase shift elements 62 serially connected byconducting lines 64. It should be noted that the phase shift elements 62can be any suitable passive or active components or combinationsthereof. The switching unit 52 comprises a plurality of switches 66,connected on one side, at first terminals 67, to a plurality of firstconducting lines 68 and on the other side, at second terminals 69, to aplurality of second conducting lines 70 shown as broken lines in thefigure. It should be noted that in the figure the first terminals 67 areshown as junctions with the first conducting lines 68. It should furtherbe noted that the plurality of first conducting lines 68 does notphysically intersect the plurality of second conducting lines 70. Thiscan be achieved, in accordance with one embodiment of the presentinvention, by positioning the plurality of first conducting lines 68 andthe plurality of second conducting lines 70 in separate planes.

In accordance with a specific embodiment of the invention the two planesare substantially parallel. If desired the space between the planes canbe filled with a dielectric plate. The plurality of second conductinglines 70 are drawn with broken lines to indicate that they are in adifferent plane from the plurality of first conducting lines 68 in thisspecific embodiment. The switches 66 are shown to be in the same planeas the first conducting lines 68, so that electrical connection betweenthe switches 66 and the second conducting lines 70 is attained byinterplane conducting lines (not shown) connected to the terminals 69.Attached to the first conducting lines 68 are switching unitinput/output ports 72, which, in the case of a phased array, areconnected to radiating elements for radiating and receivingelectromagnetic radiation. The phase shift unit 53 has, at one end aninput/output port 74 and is connected to the plurality of secondconducting lines 70 via interplane conducting lines (not shown)connected to third terminals 76.

In order to compare the number of phase shift elements and switchesrequired when using the phase control device 60 as distinct from the Nindividual M-stage conventional phase shifters as shown in FIG. 1, it isassumed that in FIG. 6 there are N input/output ports 72 and that thereare 2^(M) phase shift elements 62. Hence, there are 2^(M)N switches inthe phase control device 60. Therefore the saving in the number ofswitches when using the phase control device 60 as compared to aconventional M-stage phase shifter is ΔS=4MN−2^(M)N, whereas the savingin the number of phase shift elements is ΔP=MN-2^(M). For example, whenN=1000 and M=3, then ΔS=12000−8000=4000 and ΔP=3000−8=2992.

FIG. 7 shows a perspective view of a portion of the phase control device60 in accordance with embodiment of the invention in which the first andsecond conducting lines 68 and 70, respectively, are in separate planes.Each second terminal 69, shown in FIG. 6, is constituted of a pair ofsecond terminals 69 a, 69 b as shown in FIG. 7 connected by theinterplane conducting lines 80, shown as dotted lines. The switches 66,the first conducting lines 68 and the phase shift elements 62 along withthe phase shift unit input/output port 74, are shown to be located in an“upper plane” 82, whereas the second conducting lines are shown to belocated in a “lower plane” 84. The terms “upper” and “lower” are used inreference to the illustration of the phase control device 60 shown inFIG. 7 and do not refer to the actual orientation of the phase controldevice in practice, which can be any desired orientation. Each thirdterminal 76, shown in FIG. 6, is constituted of pair of third terminals76 a, 76 b as shown in FIG. 7, connected by interplane conducting lines80. The upper and lower planes 82 and 84 can be, for example, theopposite faces of a dielectric plate, with the interplane connectingconducting lines 80 passing through holes drilled through the dielectricplate. Although the plurality of first conducting lines 68 and theplurality of second conducting lines 70 are preferably located inseparate planes so that there will be no direct contact between them,the switches 66 and phase shift elements 62 can be located either bothin the upper plane, as shown, or both in the lower plane, or either oneof them in the upper plane and the other in the lower plane. It shouldbe appreciated that the distribution of the various components, i.e. theswitches 66, the phase shift elements 62, the conducting lines 64, andthe first and second conducting lines 68 and 70, respectively, is notnecessarily restricted to the opposite faces of a single dielectricplate and that the phase control device of the invention can also beimplemented by disposing the various components on a number ofdielectric plates arranged in a piecewise layered formation as is wellknown in chip design. The distribution of the foregoing componentsbetween the different dielectric plates can vary depending on theparticular implementation.

The operation of the phase control device for a series connected phaseshift unit will be illustrated with reference to FIG. 8, showing aschematic block diagram of a phase control device 90 having aninput/output port 91, a series connected phase shift unit 92 comprisingthree phase shift elements 93 designated by PS1, PS2 and PS3, and aswitching unit 94 comprising twenty switches 95 designated by SIJ (I=1,. . . ,4; J=1, . . . , 5) and five input/output ports 96 designated byAJ (J=1, . . . , 5). The values of the phase shifts obtained from thephase shift elements will be denoted by psK (K=1, 2, 3), that is, thephase shift element PSI gives rise to a phase shift of ps1, etc.

Consider for the sake of clarity the situation in which a current isinputted at the input/output port 91 (hence becoming, an input port inthis mode of operation) and wherein currents with various phases are tobe obtained at the input/output ports 96, which in this mode ofoperation play the role of output ports. In describing the operation ofthe phase control device it will be assumed that unless stated otherwiseall the switches 95 are turned off (i.e. they are in the “off” state),that is, they are open circuited and no current passes through them. Inorder to apply a current with a phase shift of ps3 to port As, onlyswitch S35 is turned on (i.e., it is changed from the “off” state to the“on” state). Similarly to apply a current with phase ps3 to port A4 onlyswitch S34 is turned on. In other words, in order to apply a current ofphase ps3 to output port AJ (J =1, . . . , 5) only switch S3J (J=1, . .. , 5) is turned on. In order to apply a current with a phase ps2+ps3 toport A5, the inputted current has to pass through both phase shiftelements PS2 and PS3, hence, only switch S25 is turned on. In general,to apply a current with phase ps2+ps3 to port AJ, then only switch S2J(J =1, . . . , 5) is turned on. Similarly, to apply a current with aphase ps1+ps2+ps3 to port AJ, then only switch S1J (J=1, . . . , 5) isturned on. All the phases are measured relative to the phase of thecurrent at the input port 91. Clearly, the conducting lines 100 and 102also introduce phase shifts and by varying amounts depending on whichswitches are turned on. For example, if switch S15 is turned on, thecurrent passes through a relatively small length of the conducting line102. On the other hand, if switch S11 is turned on, the current passesthrough the full length of the conducting line 102. Hence, the lengthsof the conducting lines connecting the switches to the conducting lines100 and 102 have to be suitably designed to compensate for the phaseshifts introduced by passage of a current through the conducting lines100 and 102.

One possible approach to phase compensation is illustrated schematicallyin FIG. 9 showing a block diagram of the same phase control device 90shown in FIG. 8, with the only difference that phase compensationelements 106 have been introduced in the conducting lines connecting theswitches. It should be noted that in practice, the locations of thephase compensation elements 106 are not limited to those shown in FIG.9, the only constraint being that the correct phase compensation beintroduced. Although the phase compensation elements 106 have beenillustrated as extra path lengths, it will be appreciated that the phasecompensation can be effected by any suitable phase shift component.Similarly, suitable phase compensation can also be introduced in FIGS. 6and 7.

The phase control device of the invention has been illustrated with aserially connected phase shift unit. However, the phase shift elementscan also be parallelly connected. FIG. 10 shows an illustrative blockdiagram of a phase control device 120 with a parallelly connected phaseshift unit 122 having parallelly connected phase shift elements 123commonly connected to an input/output 124. For the sake of illustration,the switching unit 126 having switches 128 and input/output ports 129,has been taken to be identical to the switching unit 94 in FIG. 8. Forthe sake of illustration, the extra path lengths used for phasecompensation, as described above, have not been shown in FIG. 10. Ifdesired a parallel connection of serially connected phase shift unitscan be formed. This can be done, for example, for the serially connectedphase shift unit shown in FIG. 9 by connecting the input/output ports 91in parallel.

In situations in which a large number of input/output ports of theswitching units of the phase control device is required, it is sometimesuseful to use a cascade configuration of phase control devices. In othersituations it is useful to connect phase control devices in parallel orin series, or in a combination thereof. To this end a phase control unitis employed from which phase control devices can be constructed. Inother words the phase shift elements and the switches may be partitionedinto phase control units, the phase shift elements in each phase controlunit being electrically interconnected and the switches in each phasecontrol unit being electrically interconnected, only to switches withinthe same phase control unit and to the phase shift elements thereof.

A cascade configuration of phase control units can comprise phasecontrol units with either serially or parallelly connected phase shiftunits. FIG. 11 shows an illustrative block diagram of a cascadeconfiguration of phase control units with serially connected phase shiftunits. Shown are four phase control units 140, 160, 180 and 200,comprising respectively, switching units 142, 162, 182 and 202 havingrespective input/output ports 144, 164, 184 and 204; and phase shiftunits 146, 166, 186, and 206 having respective input/output ports 147,167, 187 and 207. The input/output ports 204 of phase control units 200are connected to the corresponding input/output ports 147, 167 and 187of phase control units 140, 160 and 180, respectively, as shown. In thespecific application of a phased array antenna the twelve input/outputports 144, 164 and 184 are connected to the radiating elements of thephased array antenna, and input/output port 207 is the radio frequencyinput/output port of the cascaded switching units. The phase shift units146, 166 and 186 may or may not be identical, whereas the phase shiftunit 206 is, in general, different from each of the phase shift units146, 166, 186. In one particular application, the phase shift units 146,166 and 186 give rise to small phase shifts, e.g., 5°, 10° and 15°,whereas the phase shift unit 206 gives rise to large phase shifts, e.g.,30°, 60° and 90°. The cascade configuration of the phase control unitsmake it possible to produce phase shifts that are combinations of thesmall and large phase shifts.

In another application, the phase shift units 146, 166 and 186 give riseto large phase shifts and the phase shift unit 206 gives rise to smallphase shifts. FIG. 11 illustrates only one possibility of a cascadeconfiguration of phase control devices, which clearly is not restrictedto that shown and can be with any number of input/output ports and anynumber of phase control units. Furthermore, FIG. 11 illustrates a singlestage cascade configuration which can be straightforwardly generalizedto multiple cascade configurations. Other useful embodiments can beconstructed, for example, by taking the three phase control units 140,160 and 180 and electrically connecting them in parallel or in series.These embodiments are not restricted to three control units or tocontrol units with phase shift units serially connected. Furthermore,these embodiments can be constructed from a combination of phase controlunits with some of them having serially connected phase shift units andsome parallelly connected phase shift units. The same is true of cascadeformations wherein one or more of the serially connected phase controlunits shown in FIG. 11 can be replaced by parallelly connected phasecontrol units.

The present invention has been described with a certain degree ofparticularity, but it should be understood that various alterations andmodifications may be made without departing from the spirit or scope ofthe invention as hereinafter claimed.

What is claimed is:
 1. A phase control device capable of providing aplurality of phase values, comprising: a plurality of electricallyinterconnected phase shift elements; and a plurality of switches, eachswitch having a first terminal and a second terminal, the firstterminals of said switches being electrically interconnected by aplurality of first conducting lines and the second terminals of saidswitches being electrically connected to a plurality of secondconducting lines, said plurality of switches being electricallyconnected to said plurality of phase shift elements by means of saidplurality of second conducting lines.
 2. The phase control deviceaccording to claim 1, wherein said plurality of phase shift elements andsaid plurality of switches are partitioned into phase control units, thephase shift elements in each phase control unit being electricallyinterconnected and the switches in each phase control unit beingelectrically interconnected only to switches within the phase controlunit and to the phase shift elements of the phase control unit.
 3. Thephase control device according to claim 2, wherein said phase controlunits are parallelly connected.
 4. The phase control device according toclaim 2, wherein said phase control units are serially connected.
 5. Thephase control device according to claim 2, wherein some of said phasecontrol units are serially connected whereas others are parallellyconnected.
 6. The phase control device according to claim 2, whereinsaid phase control units are connected to the switches of a furtherphase control unit.
 7. The phase control device according to claim 6,wherein said plurality of phase shift elements, said plurality ofswitches and said plurality of first conducting lines are disposed onone side of a dielectric plate; whereas said plurality of secondconducting lines are disposed on the opposite of said dielectric plate.8. The phase control device according to claim 6, further comprising ina piecewise layered formation a plurality of dielectric plates, eachhaving front and rear faces, and wherein said plurality of phase shiftelements, said plurality of switches, said plurality of first conductinglines and said plurality of second conducting lines are disposed on thefaces of said dielectric plates.
 9. The phase control device accordingto claim 6, wherein said plurality of phase shift elements are seriallyconnected.
 10. The phase control device according to claim 6, whereinsaid plurality of phase shift elements are parallelly connected.
 11. Thephase control device according to any one of the above claims, whereinsaid plurality of phase shift elements, said plurality of switches andsaid plurality of first conducting lines are disposed on one side of adielectric plate; whereas said plurality of second conducting lines aredisposed on the opposite side of said dielectric plate.
 12. The phasecontrol device according to claim 11, wherein said plurality of phaseshift elements are serially connected.
 13. The phase control deviceaccording to claim 2, wherein said plurality of phase shift elements,said plurality of switches and said plurality of first conducting linesare disposed on one side of a dielectric plate; whereas said pluralityof second conducting lines are disposed on the opposite of saiddielectric plate.
 14. The phase control device according to claim 2,further comprising in a piecewise layered formation a plurality ofdielectric plates, each having front and rear faces, and wherein saidplurality of phase shift elements, said plurality of switches, saidplurality of first conducting lines and said plurality of secondconducting lines are disposed on the faces of said dielectric plates.15. The phase control device according to claim 2, wherein saidplurality of phase shift elements are serially connected.
 16. The phasecontrol device according to claim 2, wherein said plurality of phaseshift elements are parallelly connected.
 17. The phase control deviceaccording to claim 1, further comprising in a piecewise layeredformation a plurality of dielectric plates, each having front and rearfaces, and wherein said plurality of phase shift elements, saidplurality of switches, said plurality of first conducting lines and saidplurality of second conducting lines are disposed on the faces of saiddielectric plates.
 18. The phase control device according to claim 17,wherein said plurality of phase shift elements are serially connected.19. The phase control device according to claim 1, wherein saidplurality of phase shift elements are serially connected.
 20. The phasecontrol device according to claim 1, wherein said plurality of phaseshift elements are parallelly connected.
 21. The phase control deviceaccording to claim 1 wherein said first and second conducting lines areconnected to said switches such that each of said second conductinglines is connectable to one of said first conducting lines only byclosing the respective switch.
 22. The phase control device according toclaim 1 wherein said first and second connecting lines are associatedwith said plurality of switches in such a manner that when all of saidswitches are open, none of said first conducting lines is connected toany of said second conducting lines.